Remotely controlled underwater buoy



J. R. LEONARD ETAL 3,487,486

REMOTELY CONTROLLED UNDERWATER BUOY Jan. 6, 1970 3 Sheets-Sheet 1 Original Filed May 20-, 1966 JOHN R. LEONARD JAMES W. TERRY I lNVENTQR' ATTORNEY Jan. 6, 197$ J. R. LEONARD ETAL REMOTELY CONTROLLED UNDERWATER BUOY Original Filed May 20. 1966 3 Sheets-Sh9et 2 JOHN R. LEONARD JAMES w. TERRY INVENTOR ATTORNEY Y 0 U B m T A UW m w L Jan. 6, 1970 Original Filed May 20, 1966 3 Sheets-Sheet JOHN R. LEONARD JAMES W. TERRY JNVENTOR BY 60%.. A? fiw/ ATTORNEY United States Patent Ofifice 3,487,486 Patented Jan. 6, 1970 Int. Cl. B63b 21/52 US. Cl. 9-8 3 Claims ABSTRACT OF THE DISCLOSURE The specification discloses a remotely controlled buoy means which is normally submerged and rises to the surface upon receiving a signal. The buoy can be used to raise a submerged object or can be used merely to mark the underwater location of same. Structurally, the buoy is comprised of a shell having ballast means therein for maintaining the shell in a right-side-up position when it is in the water. The buoy is submerged by flooding the shell with liquid. A remote control sonar means actuates a pressurized gas source on the shell to release gas on a signal into the shell and force the liquid therefrom through a check valve in said shell thereby raising the buoy.

This is a division of application No. 552,386, filed May 20, 1966 and now United States Patent No. 3,378,067.

This invention relates to a method and apparatus for completing a subaqueous well beneath the surface of a body of water so that the wellhead thereof can be raised to the surface for maintenance and repair operations, and more particularly, to a flexible conductor pipe between the subaqueous wellbore and the production wellhead.

Heretofore, when a subaqueous well is proven and is to be placed on production, as for example in the Gulf of Mexico, usually an above-surface, bottom-supported platform is set over the well, with a riser or conductor pipe extending from the wellbore to the platform deck, and a Christmas tree (production wellhead) is mounted atop the riser pipe on the deck above the surface of the body of water. A number of directional wells can then be drilled from the deck of the platform. When the field is too shal low for directional wells, separate, spaced wells are drilled and a rudimentary support structure is constructed at the riser pipe of each well to permit an above-surface wellhead. Large ships must thread their way between these structures, and utmost care must be taken, particularly during foggy weather conditions. Signal light and other warning devices must be connected to all of the platforms and the well riser supports. However, as the more prolific producing areas become fully developed and the number of above-surface structures increases, the problems of navigation, and the resultant danger to the above-surface structures from collisions with ships, become increasingly great. While the spacing of these platforms might not appear to present a navigational hazard, at first glance, they do present one to a ships captain who is usually confronted with navigating through large open areas with few obstacles. In the Gulf of Mexico where the density of offshore platforms is increasing at a rapid rate, there have already been several collisions.

Another problem that should be considered in conjunction with above-surface completions is that of the violent storms that ravage the Gulf Coast with almost yearly frequency. These storms take their toll of any equipment which is above the surface of the water. A large production platform, if uprooted, is a tremendous economic loss, and depending upon the individual case, ten or more wells may have to be abandoned. Even the loss of a single well can have a serious effect on the economics of a companys oifshore operations.

Therefore, it would appear to be advantageous to shelter at least the production wellheads beneath the surface; however, other problems arise when a wellhead is sheltered beneath the surface of a body of water. One of the most important of these is that of servicing and maintaining the well. A diver may be used for actuating the various valves and repairing any malfunctions of the wellhead; but, even in shallow water a divers effectiveness is less than that of a man working under atmospheric conditions and moreover he is limited at this time to working in water of several hundred feet in depth.

While robetic and TFL (through flowline) tools have been developed and are available for routine servicing or workover operations, these devices are complicated and expensive and are, at this time, only used for a few limited tasks. For production purposes, it is desirable to complete a well so that certain servicing, repair, and workover operations, not as easily accomplished by remote control equipment, can be handled under atmospheric conditions. With the newly developed capabilities of the oil companies to drill and produce oil wells in the waters of the continential shelf over two hundred fifty feet, and the expected later extension of these capabilities to the con tinential slope, where the depths encountered range from six hundred to two thousand feet, the need for a diver, at this time, for routine repairs, maintenance, or workover operations, must be dispensed with.

Therefore, it is an object of this invention to provide a submerged wellhead that can be brought to the surface of a body of water for repair, maintenance, and workover operations.

Another object of this invention is to provide an improved means for remotely controlling the raising of a submerged apparatus to the surface of a body of water, the apparatus having been positioned a substantial distance beneath the surface.

Other objects and advantages of this: invention will be apparent from the following description taken with reference to the accompanying drawings, wherein is shown preferred embodiments of the invention:

FIGURE 1 is a pictorial representation of a Christmas tree mounted on the upper end of a well conductor pipe being supported in deep water by a tripod structure and having a flexible pipe section between the tripod support structure and the wellhead;

FIGURE 2 is a cross-sectional view of the flexible section of the well conductor pipe shown in FIGURE 1;

FIGURE 3 is an elevational view, partly in cross section, showing a remotely controlled buoy of the present invention connected to a subaqueous wellhead and used as a locating marker therefor; and

FIGURE 4 is a side elevational view of a shallow water installation in which the Christmas tree is mounted on the upper end of a well conductor pipe projecting only from the marine bottom. The conductor pipe has a flexible section permitting it to be bent over so that the Christmas tree rests near the marine bottom and is spaced therefrom by the periphery of a buoy mounted on the upper end of the conductor pipe.

Referring now to the drawings, more in detail, by character reference, there is shown in FIGURE 1 a conductor pipe 10 protruding from the subaqueous marine bottom 12 and terminating just below a designated distance a beneath the surface 14 of the body of water. The distance a indicates a sheltered depth at: which apparatus will not be substantially subject to surface conditions. As to this sheltered depth at which the wave and tital actions and surface storms would no longer be a substantial problem, this would vary with the total depth of the water. A

3 figure used with present subsurface completions off California is one hundred feet. Of course, in the shallow water of the Gulf Coast twenty-five to fifty feet might be more appropriate.

The conductor pipe is illustrated as capped by a production wellhead or Christmas tree 16, shown schematically, and is braced by a tripod support structure 18 set on the marine bottom 12. The rigid conductor pipe section 20, below the support structure 18 is identical to conductor pipes or surface casings that are normally utilized in offshore installations. Connected to the upper end of the rigid conductor pipe section 20, above the support 18, is a flexible conductor pipe section 22 with a rigid upper conductor pipe section 24 connected to its free. end- The upper rigid conductor pipe section 24 in turn terminates in the Christmas tree 16 from which extends a fiow or shipping line 26 for carrying the production products from a subaqueous well (not shown) to separator or storage facilities (not shown) onshore, on the marine bottom, or on an above-surface platform. The flowline 26, originating at the Christmas tree I16, has a flexible portion between the Christmas tree 26 and the upper end of the support structure 18; a rigid portion, preferably of a high strength material, such as steel pipe, paralleling the conductor pipe down to the marine bottom 12; and a flexible portion laying along the marine bottom 12. The portion of the flowline 26 paralleling the conductor pipe 10 would be supported by the conductor pipe :10 at intervals.

Fixed to the upper end of the support structure 18 is an inverted conical framework 28 terminating in a large diameter tubular rim 30 for abutting the rigid conductor pipe section 24 and supporting the Christmas tree 16 regardless of the direction in which the flexible conductor pipe section 22 bends as the conductor pipe 10 is lowered beneath the surface 14 of an offshore body of water. Also connected to the conductor pipe 10 is a buoy 32 having a sonar-controlled variable buoyancy. The buoy 32 is attached to the conductor pipe 10 by a cable 34 fastened at its ends to padeyes 36 spaced along the length of the conductor pipe 10 above the upper end of the support structure 18 and slidably strung through a padeye 38 fixed to the lower end of the buoy 32.

The construction of the flexible section 22 is shown in more detail in FIGURE 2. The flexible section 22 consists of a plurality of fluidtight ball joints 40 (representatively denoted) bolted together, and to the rigid conductor pipe sections 20 and 24 by end flanges 42 to form as flexible a section 22 as necessary. Each of the ball joints 40 consists of an inner spherical shell 44 which has diametrically opposed circular openings 46 and 48 formed therethrough. The smaller circular opening 46 is extended by a tubular portion 50 integrally connected to the spherical shell 44 and having an end flange 42 fixed thereto. An outer partially spherical shell 52, less than a hemisphere in extent, and terminating in a planar rim 54, slidably mates with the inner spherical shell 44 over the larger circular opening 48. The partially spherical shell 52 has a tubular portion 56 extending therefrom coincident with a central circular opening 58 equal in size to the smaller opening 46 of the spherical shell 44, the tubular portion 56 also having an end flange 42. An annular element 60, having an inner diameter of less than the outer diameter of the spherical shell 44, is mounted thereon opposite the rim -54 of the partially spherical shell 52. A packing -62 is included in the space between the annular element 60 and the rim 54. Bolting the annular element 60 and the outer shell 52 together by means of a plurality of equally spaced bolts 64 causes a fluidtight seal between the spherical shells 44 and 52 and the packing 62, while permitting -a limited universal movement therebetween. Although the allowable degree of movement of each of the joints 40 may be varied, it has been found that 20 is a good engineering compromise. If a 90 bend is desired, five joints 40 will be required,

Production tubing is set within the conductor pipe 10 and consists in part of a flexible section coincident with the flexible section 22 of the conductor pipe 10, made up of tubular elements 66 interconnected by fluidtight flexible joints 68 which may be identical in type, although smaller in size than the ball joints 40. A lower rigid section 70 of the production tubing, projecting out of the subaqueous well beneath the marine bottom 12, would be identical to that found in prior art wells. An upper rigid production tubing section 72 is fixed to the outer-most flexible joint 68 and is operatively connected into the Christmas tree I16.

It can be seen (in FIGURE 1) that the conductor pipe 10 and the included production tubing are arranged to be bent over into a position in which the Christmas tree 16 rests on the rim 30 a safe distance beneath the surface 14. In such a position, the subsea in stallation would not be a navigational hazard and would be protected from surface conditions, such as wind, waves, and violent storms. The Weight of the Christmas tree 16 and the upper rigid conductor pipe section 20 is alone enough to cause the conductor pipe 10 to bend into the sheltered position. In reasonably calm water the conductor pipe 10 will hold this position until raised. Any movement of the upper end of the conductor pipe 10 caused by shifting currents and tides will not affect the depth at which the Christmas tree 16 rests due to the circular configuration of the rim 30.

To raise the Christmas tree 16 back to the surface 14 for repair or workover operations, the buoy 32 is activated by a sonar signal, causing it to fill with gas and thereby expelling the water therefrom (as will be explained). The buoyancy of the buoy 32 carries it toward the surface 14 trailing the conductor pipe 10 along by means of the cable 34. The buoy 32 may be designed to bring the Christmas tree 16 completely out of the water or it may only rise enough so that the buoy 32 itself shows on the surface. In the latter case a barge or derrick nearby would be used to haul in the cable 34 until the Christmas tree 16 has reached the desired position above the surface 14 of the water.

In FIGURE 3 the buoy 32 is shown floating on the surface 14 of a body of Water and connected to a permanently submerged Christmas tree 16 of a subaqueous well by a cable 34. Although in this view it is shown merely as a marker (which would be another use for such a buoy), it would be of the same construction as that illustrated in FIGURE 1, although smaller. At 32 the same buoy, resting on the bottom, is shown in expanded cross-section (at the right). The cable 34' is stored on the oceans bottom until it is needed and the chance of this cable being broken, or the buoy damaged during severe storms, as is possible if a continuously floating buoy is utilized, is reasonably overcome. The buoy 32' consists of a hollow shell 74 having a ballast section 76 therein. The ballast section 76 is designed to hold the buoy 32 firmly to the marine bottom 12, as well as to insure proper alignment of a sonar antenna 78. A check valve 80, biased closed, is fitted in the shell 74 of the buoy 32 to permit the expelling of the water therefrom due to internal pressure. The water is expelled by means of high pressure gas, in this case nitrogen, carried in a capsule 82 within a dome 84 on the shell 74 of the buoy 32. An actuator 86 is operatively connected to the sonar antenna 78, and by conventional means, will release the nitrogen gas from the capsule 82 on command. Such a release means could be an explosively driven pin that would puncture the nitrogen capsule to permit the gas to escape therefrom or a battery-operated solenoid that would unscrew a cap from the capsule. Such actuators are well known, and it is not believed necessary to discuss the details of such a device. A plug 88 is threaded into one end of the shell 74. By removing this plug 88, gas pressure can be released and the buoy 32' reflooded.

Now referring to FIGURE 4, the invention is shown as it would be utilized in fairly shallow water of approximately one hundred feet or less. The depth at which a supplementary support structure is not necessary is determined by a number of factors including the length of conductor pipe that a buoy could lift to the surface. The lower rigid conductor pipe section 20 extends only a short distance up from the marine bottom 12, supported in a landing base 90, above which it is continued as a flexible section 22. The flexible section 22 of the conductor pipe as in FIGURE 1 terminates in an upper rigid conductor pipe section 24 which is capped by a Christmas tree 16. The flexible section 22 would be of the same length as that shown in FIGURE 1, the length being determined only by the amount of bending required.

A second embodiment of the buoy is shown which incorporates the feature of spacing the Christmas tree 16 from the marine bottom 12. The buoy, generally designated 92, mounted directly on the conductor pipe section 24, has a large diameter ring-shaped element forming a hollow toroidal shell 94 supported on the conductor pipe section 24 by a rigidly fixed inner sleeve or hub 96 and a plurality of interconnecting radial spokes 98. The toroidal shell 94 serves the double functions of a variably buoyant compartment and a spacer to keep the Christmas tree 16 away from the marine bottom 12 regardless of what direction the conductor pipe 10 has been bent. The design of the spacer-buoy 92 can be varied, within the concept of the invention, by enlarging the dimensions or the hub 96 and constricting the toroidal diameter of the shell 94, the hub having the hollow compartment and functioning as the buoy while the outer shell is only a spacer ring. However, as envisioned, as the preferred embodiment, the toroidal shell 94 would be the hollow compartment and would be large enough to act as a floating base to support the Christmas tree 16 straight up out of the Water when it is actuated.

Although no dome 84, carrying the sonar antenna 78, the nitrogen capsule 82, and the actuator 86, is illustrated in this view, one would be necessary if the buoy is to be remotely actuated. The dome 84 could be mounted on the toroidal shell 94 or on the conductor pipe 10.

What is claimed is:

1. A remotely controlled buoy means comprising:

an enclosed shell, said shell having an opening through which said shell can be filled with liquid;

means normally closing said opening;

ballast means aflixed to the bottom, interior portion of said shell, said ballast means being so positioned whereby said shell will rest on its bottom exterior portion in a right-side-up position when said buoy is submerged;

valve means extending through said ballast means and said bottom portion of said shell to establish fluid communication between the interior of said shell and the exterior thereof when said valve means is in an open position;

means to bias said valve means normally to a closed position;

means for containing gas under high pressure aflixed to the upper exterior portion of said shell; and

remotely actuated means affixed to said upper exterior portion of said shell for releasing said gas from said containing means into said shell to force any liquid in said shell against said bias means of said valve means to open same to allow said liquid to be expelled therethrough.

2. The buoy of claim 1 wherein:

said remotely actuated gas releasing means comprises a sonar responsive device.

3. The buoy of claim 2 wherein:

said enclosed shell is of elongated configuration having its elongated axis parallel to the upper and bottom portions of said shell and having a first end and a second end and wherein the gas from said containing means enters said shell near said first end and said valve means is located near its second end; and

means on the exterior of second end adapted to receive a cable or the like for mooring said buoy.

References Cited UNITED STATES PATENTS 1,274,230 7/1918 De Arazoza 11452 3,178,736 4/1965 Gross 9-8 3,252,439 5/1966 Shatto et al.

FOREIGN PATENTS 1,006,731 10/1965 Great Britain.

MILTON BUCHLER, Primary Examiner J. L. Forman, Assistant Examiner US. Cl. X.R. 114-16, 235 

